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Reducing memory fragmentation in network applications with dynamic memory allocators optimized for performance

COMPUTER COMMUNICATIONS 2006年第13-14期29卷 2612-2620页

作者： Mamagkakis, Stylianos Baloukas, Christos Atienza, David Catthoor, Francky Soudris, Dimitrios Thanailakis, Antonios Democritus Univ Thrace VLSI Design & Testing Ctr GR-67100 Xanthi Greece Univ Complutense Madrid DACYA E-28040 Madrid Spain Ecole Polytech Fed Lausanne LSI CH-1015 Lausanne Switzerland IMEC VZW B-3001 Louvain Belgium

The needs for run-time data storage in modern wired and wireless network applications are increasing. Additionally, the nature of these applications is very dynamic, resulting in heavy reliance on dynamic memory allocation. The most significant problem in dynamic memory allocation is fragmentation, which can cause the system to run out of memory and crash, if it is left unchecked. The available dynamic memory allocation solutions are provided by the real-time Operating Systems used in embedded or general-purpose systems. These state-of-the-art dynamic memory allocators are designed to satisfy the run-time memory requests of a wide range of applications. Contrary to most applications, network applications need to allocate too many different memory sizes (e.g., hundreds different sizes for packets) and have an extremely dynamic allocation and de-allocation behavior (e.g., unpredictable web-browsing activity). Therefore, the performance and the de-fragmentation efficiency of these allocators is limited. In this paper, we analyze all the important issues of fragmentation and the ways to reduce it in network applications, while keeping the performance of the dynamic memory allocator unaffected or even improving it. We propose highly customized dynamic memory allocators, which can be configured for specific network needs. We assess the effectiveness of the proposed approach in three representative real-life case studies of wired and wireless network applications. Finally, we show very significant reduction in memory fragmentation and increase in performance compared to state-of-the-art dynamic memory allocators utilized by real-time Operating Systems. (c) 2006 Elsevier B.V. All rights reserved.

关键词： memory fragmentation dynamic memory allocator network application performance optimized operating systems customization

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ELIMINATING memory-fragmentation WITHIN PARTITIONABLE SIMD SPMD MACHINES

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IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 1991年第3期2卷 290-303页

作者： NICHOLS, MA SIEGEL, HJ DIETZ, HG QUONG, RW NATION, WG IBM CORP ENDICOTTNY 13760 PURDUE UNIV SCH ELECT ENGNPARALLEL PROC LABW LAFAYETTEIN 47907

Efficient data layout is an important aspect of the compilation process. A model for the creation of "perfect" memory maps for large-scale parallel machines capable of user-controlled partitionable SIMD/SPMD operation is developed. The term "perfect" implies that no memory fragmentation occurs and ensures that the memory map size is kept to a minimum. The major constraint on solving this problem is one based on the single program nature of both the SIMD and SPMD modes of parallelism. Specifically, it is assumed all processors within the same submachine use identical addresses to access corresponding data items in each of their local memories. Necessary and sufficient conditions are derived for being able to create "perfect" memory maps and these results are applied to several partitionable interconnection networks.

关键词： COMPILERS INTERCONNECTION NETWORKS memory fragmentation PARALLEL PROCESSING PARTITIONABLE MACHINES PASM SIMD SPMD

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Geometrical optics and models of computer memory fragmentation

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STUDIES IN APPLIED MATHEMATICS 2003年第2期111卷 185-238页

作者： Knessl, C Univ Illinois Dept Math Stat & Comp Sci Chicago IL 60607 USA

We analyze a two-dimensional difference equation that arose in a stochastic model of memory fragmentation in computers. We use the ray method of geometrical optics, and other singular perturbation methods, to solve this equation asymptotically. The asymptotic limit corresponds to one of heavy system usages. We interpret the results from the ray method probabilistically.

关键词： Stochastic-model Storage Allocation Queues singular perturbation method computer memory Computers Storage Geometrical optics Queue memory fragmentation Difference equation asymptotic Stochastic models allocation

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Estimating internal memory fragmentation for Java programs

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JOURNAL OF SYSTEMS AND SOFTWARE 2002年第3期64卷 235-246页

作者： Skotiniotis, T Chang, JEM Iowa State Univ Dept Elect & Comp Engn Ames IA 50011 USA

Dynamic memory management has been an important part of a large class of computer programs and with the recent popularity of object oriented programming languages, more specifically Java, high performance dynamic memory management algorithms continue to be of great importance. In this paper, an analysis of Java programs, provided by the SPECjvm98 benchmark suite, and their behavior, as this relates to fragmentation, is performed. Based on this analysis, a new model is proposed which allows the estimation of the total internal fragmentation that Java systems will incur prior to the programs execution. The proposed model can also accommodate any variation of segregated lists implementation. A comparison with a previously introduced fragmentation model is performed as well as a comparison with actual fragmentation values that were extracted from SPECjvm98. Finally the idea of a test-bed application that will use the proposed model to provide to programmers/developers the ability to know, prior to a programs execution, the fragmentation and memory utilization of their programs, is also introduced. With this application at hand developers as well as designers of applications could better assess the stability, efficiency as well reliability of their applications at compile time. (C) 2002 Elsevier Science Inc. All rights reserved.

关键词： memory fragmentation buddy system Java virtual machine

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Skin conductance and memory fragmentation after exposure to an emotional film clip in depersonalization disorder

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PSYCHIATRY RESEARCH 2010年第3期177卷 342-349页

作者： Giesbrecht, Timo Merckelbach, Harald van Oorsouw, Kim Simeon, Daphne Maastricht Univ Dept Clin Psychol Sci NL-6200 MD Maastricht Netherlands Beth Israel Deaconess Med Ctr Albert Einstein Coll Med New York NY 10003 USA

It is often assumed that when confronted with an emotional event, patients with DPD inhibit information processing. It is also thought that this fosters memory fragmentation. This hypothesis has not been tested in chronic depersonalization. The aim of this study was to investigate the temporal pattern of autonomic responding to emotional material in depersonalization disorder, along with concomitant deficits in subjective and objective memory formation (i.e., difficulties to form a coherent narrative consisting of an ordered sequence of events). Participants with depersonalization disorder (n = 14) and healthy control participants (n = 14) viewed an emotional video clip while their skin conductance (SC) levels were measured. Peritraumatic dissociation was measured before and after the clip, and memory performance was measured 35 min after viewing. Compared to controls, depersonalized participants exhibited a distinctly different temporal pattern of autonomic responding, characterized by an earlier peak and subsequent flattening of SCLs. Maximum SCLs did not differ between the two groups. Moreover, unlike the control group, depersonalized participants showed no SC recovery after clip offset. In terms of memory performance, patients exhibited objective memory fragmentation, which they also reported subjectively. However, they did not differ from controls in free recall performance. Apparently, emotional responding in DPD is characterized by a shortened latency to peak with subsequent flattening and is accompanied by memory fragmentation in the light of otherwise unremarkable memory functioning. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

关键词： Depersonalization Skin conductance Time course of affective responding memory fragmentation

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Controlling Physical memory fragmentation in Mobile Systems 15

Controlling Physical Memory Fragmentation in Mobile Systems

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14th ACM SIGPLAN International Symposium on memory Management (ISMM)

作者： Kim, Sang-Hoon Kwon, Sejun Kim, Jin-Soo Jeong, Jinkyu Korea Adv Inst Sci & Technol Daejeon South Korea Sungkyunkwan Univ Suwon South Korea

ISBN: (纸本)9781450335898

Since the adoption of hardware-accelerated features (e.g., hardware codec) improves the performance and quality of mobile devices, it revives the need for contiguous memory allocation. However, physical memory in mobile systems is highly fragmented due to the frequent spawn and exit of processes and the lack of proactive anti-fragmentation scheme. As a result, the memory allocation for large and contiguous I/O buffers suffers from highly fragmented memory, thereby incurring high CPU usage and power consumption. This paper presents a proactive anti-fragmentation approach that groups pages with the same lifetime, and stores them contiguously in fixed-size contiguous regions. When a process is killed to secure free memory, a set of contiguous regions are freed and subsequent contiguous memory allocations can be easily satisfied without incurring additional overhead. Our prototype implementation on a Nexus 10 tablet with the Android kernel shows that the proposed scheme greatly alleviates fragmentation, thereby reducing the I/O buffer allocation time, associated CPU usage, and energy consumption.

关键词： memory fragmentation Mobile systems

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Perceptual memory representations and memory fragmentation as predictors of post-trauma symptoms

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BEHAVIOURAL AND COGNITIVE PSYCHOTHERAPY 2007年第3期35卷 259-272页

作者： Buck, Nicole Maastricht Univ Fac Med & Hlth Sci Dept Med Clin & Expt Psychol NL-6200 MD Maastricht Netherlands Univ Amsterdam NL-1012 WX Amsterdam Netherlands Univ Utrecht NL-3508 TC Utrecht Netherlands Univ Hosp Maastricht Maastricht Netherlands

Ehlers and Clark (2000) hypothesize that persistent PTSD is explained by a predominance of data-driven processing and a lack of conceptually-driven processing of the trauma. Data-driven/conceptually-driven processing is thought to relate to perceptual memory representations and memory fragmentation. The present study measured the result of data-driven/conceptually-driven processing in three ways: on utterance level by assessing 1) the ratio between perceptual and conceptual memory representations and 2) utterance disorganization, and 3) on narrative level by assessing the incoherence of the trauma narrative. Twenty-nine patients discharged from the Intensive Care Unit (ICU) were assessed within two weeks after ICU discharge and at 4 months follow-up. The present study tested whether perceptual memory representations, narrative disorganization and narrative incoherence immediately after ICU discharge are related to post-trauma symptomatology. If so, whether these variables are specific for PTSD as compared to depression. Data-driven/conceptually-driven processing was related to PTSD and Depression symptoms on utterance level. Although narrative incoherence did not predict PTSD symptoms, it was predictive of depression symptoms. The present study showed the viability of the data-driven/conceptually-driven conceptualization in explaining post-trauma symptomatology.

关键词： emotional-trauma posttraumatic stress disorder cognitive processes data-driven and conceptually-driven processing memory fragmentation objective assessments

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A Quantitative Approach for memory fragmentation in Mobile Systems 1st

A Quantitative Approach for Memory Fragmentation in Mobile S...

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1st International Conference on Smart Computing and Communication (SmartCom)

作者： Li, Yang Liu, Duo Zhang, Jingyu Long, Linbo Chongqing Univ Coll Comp Sci Chongqing Peoples R China Chongqing Univ Posts & Telecommun Coll Comp Sci & Technol Chongqing Peoples R China

ISBN: (纸本)9783319520155;9783319520148

Mobile devices are equipped with many hardware accelerators to improve the performance and there are a bunch of third-party applications with rich-features in the application market. However, these applications always request large and contiguous physical memory as IO buffers and we observe that physical memory is severely fragmented after the mobile system runs for several hours. As a result, the memory allocation for such large and contiguous IO buffers will result in high latency and power consumption. Thus, this paper proposes a global memory fragmentation quantification approach that summarizes memory blocks access pattern and measures the allocation time of different order's memory block dynamically. Our evaluation on Android Kitkat shows that the global memory fragmentation is very precise to reflect the fluency of whole system.

关键词： Mobile systems memory fragmentation Quantification Defragmentation Anti-fragmentation

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Controlling Physical memory fragmentation in Mobile Systems

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ACM SIGPLAN NOTICES 2015年第11期50卷 1-14页

作者： Kim, Sang-Hoon Kwon, Sejun Kim, Jin-Soo Jeong, Jinkyu Korea Adv Inst Sci & Technol Daejeon South Korea Sungkyunkwan Univ Suwon South Korea

关键词： memory fragmentation Mobile systems

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The intelligent memory allocator selector

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COMPUTER LANGUAGES SYSTEMS & STRUCTURES 2015年第PartC期44卷 342-354页

作者： Ulgen, Onur Avci, Mutlu Cukurova Univ Fac Engn & Architecture Dept Comp Engn Adana Turkey Cukurova Univ Fac Engn & Architecture Dept Biomed Engn Adana Turkey

memory fragmentation is a serious obstacle preventing efficient memory usage. Garbage collectors may solve the problem;however, they cause serious performance impact, memory and energy consumption. Therefore, various memory allocators have been developed. Software developers must test memory allocators, and find an efficient one for their programs. Instead of this cumbersome method, we propose a novel approach for dynamically deciding the best memory allocator for every application. The proposed solution tests each process with various memory allocators. After the testing, it selects an efficient memory allocator according to condition of operating system (OS). If OS runs out of memory, then it selects the most memory efficient allocator for new processes. If most of the CPU power was occupied, then it selects the fastest allocator. Otherwise, the balanced allocator is selected. According to test results, the proposed solution offers up to 58% less fragmented memory, and 90% faster memory operations. In average of 107 processes, it offers 7.16 +/- 2.53% less fragmented memory, and 1.79 +/- 7.32% faster memory operations. The test results also prove the proposed approach is unbeatable by any memory allocator. In conclusion, the proposed method is a dynamic and efficient solution to the memory fragmentation problem. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： memory fragmentation memory allocator Garbage collection Virtual machine

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